Single-Crystal, Polarized Raman-Scattering Study of the Molecular and Lattice Vibrations for the Energetic Material Cyclotetramethylenetetranitramine, β-Polymorph (β-HMX)

The single-crystal polarized Raman spectra for cyclotetramethylenetetranitramine, β-polymorph (β-HMX), are reported over the region of 10 to 3150 cm -1 . While the agreement with previous Raman studies is quite good, a consistent interpretation of the Raman spectra is provided through assignment of fundamental modes, overtones, and combination bands. This affords the first assignment of all six Raman-active optical phonons of β-HMX. It was found that three A g symmetry librations are accidentally degenerate with three B g optical phonons. The importance of these phonons for coupling with “doorway” Raman-active modes of β-HMX is discussed in relation to proposed vibrational mechanisms for the initiation of detonation.